THE DEVELOPMENT OF TEXTURE AT INTERMEDIATE STAGES OF COLD ROLLING IN LOW CARBON BCC STEEL

Abstract

Much of the literature on cold rolled texture focuses on the various textures that are present after a standard amount of cold roll reduction, usually 70-90 %. Also mentioned is the effect that total cold roll reduction has on the final cold roll texture. However, very little investigation has focused on the development of texture at various intermediate stages of cold roll reduction. This thesis describes the texture evolution during the cold rolling of two commercial steels that are used extensively in stamping operations. The cold rolling mill was a 5 stand, 4 high continuous mill located at Dofasco Steel Inc. in Hamilton, Ontario. The author at the time was in a position to have the mill stopped, and have samples cut from the strip at the entry and exit to the mill and also between each roll stand. This was done on six occasions, three times each for each of the two different steels. The samples were prepared for metallographic examination in a diffractometer, and pole figures were generated using software supplied by Los Alamos Research Laboratories, New Mexico. The pole figures defined how the texture evolved as the steel strip progressed through the mill. The Los Alamos software also enabled crystallite orientation distribution functions (CODF’s) to be generated. Amongst other things the CODF allows textures to be described in terms of the dominant ideal crystallographic orientations. In turn these ideal orientations were qualitatively related to the level of the normal anisotropy parameter ( F ) in recrystallized samples of the two steels. The F -value has been used extensively in the steel industry as a measure of formability, in particular the deep drawability. The experimental results from this investigation are generally in agreement with published work that has modelled the texture evolution in cold rolled, low carbon steels.